By default use private/tftpboot/ filefolder for tftp download and upload:

sudo chmod 777 /private/tftpbootsudo chmod 777 /private/tftpboot/*

2, setup tftp route in 6800

I want to download/upload from/to mgmt port, mgmt port belongs to a separated management vrf. In order to make tftp server IP routed correctly, we need add the following configuration into the chassis:

cat6k#ip tftp source-interface mgmt0

3, Now it is ready for tftp download/upload to OS x from/to vrf enabled Chassis.